1. Field of the Invention
The present invention relates to an imaging apparatus and an evaluation value generation apparatus.
Priority is claimed on Japanese Patent Application No. 2011-286029, filed Dec. 27, 2011, the content of which is incorporated herein by reference.
2. Description of Related Art
As controls of photography in recent imaging apparatus such as digital cameras, there are controls such as auto exposure (AE), auto white balance (AWB), and auto focus (AF).
In control of AE, AWB and AF in a conventional imaging apparatus, evaluation values (an AE evaluation value, an AWB evaluation value, and an AF evaluation value) for the respective controls are generated based on a pixel signal output from a solid-state imaging device (hereinafter referred to as an “image sensor”). In this case, in the conventional imaging apparatus, evaluation value generation units (an AE evaluation value generation unit, an AWB evaluation value generation unit, and an AF evaluation value generation unit), which generate the respective evaluation values while acquiring the pixel signal output from the image sensor, generate the respective evaluation values in real time (see Japanese Unexamined Patent Application, First Publication No. 2008-5048).
FIG. 10 is a block diagram illustrating a schematic configuration of a conventional imaging apparatus. In FIG. 10, the imaging apparatus includes an image sensor, an imaging processing unit, an image processing unit, a DRAM (Dynamic Random Access Memory) controller, a DRAM, a display processing unit, a display device, and a CPU. Further, in FIG. 10, a schematic internal configuration of the imaging processing unit is also shown. In FIG. 10, the imaging processing unit includes an imaging IF (interface) unit, a preprocessing unit, an AE evaluation value generation unit, an AWB evaluation value generation unit, an AF evaluation value generation unit, and an output DMA (Direct Memory Access) unit.
In the conventional imaging apparatus illustrated in FIG. 10, the imaging IF unit acquires a pixel signal from the image sensor, and outputs the acquired pixel signal as image data to the preprocessing unit. The preprocessing unit performs various processing on the image data input from the imaging IF unit. In FIG. 10, an example of the preprocessing unit including three processing units that perform the respective processing is illustrated. The preprocessing unit outputs final image data obtained by the respective processing units sequentially performing the processing to the AE evaluation value generation unit, the AWB evaluation value generation unit, the AF evaluation value generation unit, and the output DMA unit.
The AE evaluation value generation unit, the AWB evaluation value generation unit, and the AF evaluation value generation unit generate the evaluation values based on the image data input from the preprocessing unit. The AE evaluation value generation unit, the AWB evaluation value generation unit, and the AF evaluation value generation unit store the generated AE evaluation value, the generated AWB evaluation value, and the generated AF evaluation value in the DRAM via the DRAM controller, respectively. Using the respective evaluation values stored in the DRAM, the CPU performs the control of AE, AWB and AF in the conventional imaging apparatus.
The AE evaluation value generation unit, the AWB evaluation value generation unit, and the AE evaluation value generation unit may hold the generated AE evaluation value, the generated AWB evaluation value, and the generated AF evaluation value in registers in the evaluation value generation units, respectively, instead of storing the generated evaluation values in the DRAM. In the case of such a configuration, the CPU receives a notification indicating that generation of the evaluation values has been completed from the respective evaluation value generation units and then reads the respective evaluation values held in the registers of the respective evaluation value generation units. Using the respective read evaluation values, the CPU performs control of AE, AWB and AF in the imaging apparatus.
Further, the output DMA unit stores the image data input from the preprocessing unit in the DRAM via the DRAM controller. Here, the image data stored in the DRAM becomes original image data that is image-processed by the image processing unit later.
With this configuration, the conventional imaging apparatus generates the AE evaluation value, the AWB evaluation value, and the AF evaluation value while acquiring the pixel signal output from the image sensor in real time. Thus, in the conventional imaging apparatus, the AE evaluation value, the AWB evaluation value, and the AF evaluation value for control of AE, AWB, and AF can be immediately generated.